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ORP sensor

The ORP sensor BT57i measures the ability of a solution to act as an oxidizing or reducing agent. ORP stands for oxidation-reduction potential also known as Redox Potential.The ORP sensor consists of an ORP electrode and an amplifier. The ORP electrode has two components: a measuring half cell comprised of platinum metal immersed in the test solution in which the redox reaction is taking place, and a reference half cell (sealed gel-filled Ag/AgCl) surrounded by a salt solution. The measuring platinum electrode serves as an electron donor or electron acceptor depending upon the test solution and the reference electrode is used to supply a constant stable output for comparison. The ORP electrode measures the redox potential – difference in the voltage generated by the platinum measuring electrode and the voltage produced by the reference electrode - in the range of -450 to +1100 mV. Readings towards the positive region of this range indicate a strong oxidizing agent, while readings towards the negative region indicate a strong reducing agent.

Redox reactions control the behavior of many chemical constituents in drinking water, wastewater and aquatic environments. The reactivity and solubility of critical elements in living systems are strongly dependent on redox conditions. ORP values are used much like pH values to determine water quality. For example for swimming pools at a normal pH value between 7.2 and 7.6, the ORP value must be kept above 700 mV to kill unwanted organisms. In contrast, in order to support life, natural waters need a much lower ORP value. Generally ORP values above 400 mV are harmful to aquatic life. The ORP sensor can also be used for redox titrations to determine the equivalence point in an oxidation-reduction reaction.

The CMA ORP sensor can be directly connected to the analog BT inputs of the CMA interfaces.Attention: The sensor cable BT - IEEE1394 needed to connect the sensor to an interface is not supplied with the sensor and has to be purchased separately (CMA Art. Nr BTsc_1).

Technical specifications of the sensor are described in its User's guide.